1. Field of the Invention
The present invention relates generally to a battery powered, illuminated ornament. More specifically, the present invention is a battery powered, illuminated ornament that can provide even illumination of the exterior surface of the ornament, never appears to turn the light source completely off, and can run for an entire holiday season on a single set of batteries.
2. Background
The use of illuminated ornaments and decorations to celebrate various holidays is well known. Strings of lights consisting of small incandescent or LED bulbs, often referred to as Christmas Tree Lights or light strings, are a typical example. These are typically just bare bulbs spaced along a string of conducting wires, usually powered from the AC house mains. When ambient light levels are high, these light strings appear as a multitude of brightly lit, often multicolored, points of light. At lower ambient light levels, they also serve to illuminate portions the object which supports them, typically a Christmas tree, and any other decorations that might be near the string of lights. Sometimes the bare bulbs on these light strings are placed within a translucent ornament, which changes the appearance from a single point of light into an illuminated shape. A major drawback to using string lights, with or without the attached ornament, is that a source of AC power is required. Typically this requires the use of long extension cords to supply power to the area that is to be illuminated, especially when the light strings are used in outdoor locations. Another drawback is that since the bulbs are spaced along the string at an interval determined by the manufacturer, there is very little flexibility in the placement of the bulbs or, if present, the attached translucent ornament. A further drawback is that when the ambient light level is high, the conductive wires between each bulb are visible and detract from the intended decorative effect.
Another variety of illuminated ornament uses a light source inside the ornament and a short cord with a plug that matches the sockets used in a typical Christmas tree light string. At the desired location, one of the bulbs is removed from the light string, and the plug on the ornament is inserted into the empty socket. While this allows the glowing ornament to be positioned with more flexibility, it still must be located near the string of lights and does not address the difficulties of having to supply AC power for the light string or address the issue of unsightly wiring.
One way to eliminate the need to run AC power to the desired location of the ornament is to use one or more batteries to supply power for the light source. Small coin cell batteries can be concealed within an ornament and their small size allows an even illumination of the ornament with a minimal amount of shadowing caused by internal structures within the ornament. However, the capacity of these small batteries is limited and they can provide a visibly attractive light level for only a short amount of time. During a typical holiday season, the batteries need to be replaced quite often resulting in increased operating cost and increased inconvenience. To increase the useful battery life, one option is to blink the light source on only briefly and leave it off most of the time. While this approach can greatly extend battery life, for the large majority of the time the ornament is completely dark which greatly reduces its decorative effect.
Another option to increase battery life is to use larger batteries. These can be placed in an external battery enclosure and connected to the ornament by wires, but the wires and the battery enclosure are unsightly and compromise the decorative effect of the ornament. The battery enclosure can be integrated into the design, for instance as a rectangular base that the ornament is attached to, but this limits the ornament designs that are possible. For instance, a typical shape for Christmas tree ornaments is a globe. Attaching an enclosure for large batteries to the outside of the globe is not possible while maintaining the traditional shape.
Non-coin cell type batteries can also be placed within the ornament. In general they will have a larger volume and therefore higher capacity for a given battery technology. This approach solves the problems associated with external battery packs, either attached by wires or attached to the outside of the ornament. While providing more battery capacity, the relatively small size of most ornaments prevents the use of batteries that are large enough to power the light source at a visibly attractive level for an entire holiday season. When using a single light source, the larger battery placed within the ornament also blocks light coming from the light source from illuminating the entire surface of the ornament evenly. The shadows caused by the relatively large internal battery places restrictions on the type of lighting effects that can be achieved on the surface of the ornament. For instance, it is difficult to illuminate a spherical ornament evenly since the internal battery will cause dark shadows over much of the ornament's surface. Multiple light sources could be placed around the internal battery to evenly illuminate the surface, but this adds to the cost and complexity of the ornament.
Another difficulty occurs when using internal non-coin cell batteries in a spherical ornament that is intended to imitate the appearance of a traditional spherical Christmas tree ornament. This type of traditional ornament is often a blown glass sphere with a small opening surrounded by a raised ridge on one end. An ornamental cap with a means for hanging the ornament is attached to this opening. There are no other openings or seams in the ornament. In order to maintain the appearance of this traditional ornament in an ornament that has internal batteries, it is necessary that the batteries be inserted into the ornament through an opening that approximates the opening in a traditional ornament in size and location. This places restrictions on the size and orientation of the internal batteries making it more difficult to achieve even illumination and still provide enough battery capacity to provide a visibly attractive light level for an entire holiday season.
Another means to extend battery life is to reduce the light intensity to a very low level, thus requiring less current to be drawn from the internal batteries. As described in U.S. Pat. No. 6,992,591, it is possible to illuminate a large surface at a very low level and achieve extended battery life. While quite visible and attractive during low ambient light level conditions, this type of illumination is a little monotonous. The introduction of brief periods of higher intensity with a pleasing pattern can greatly improve the decorative effect of such an ornament.
For ornaments intended for outdoor use, it is often desirable to use a light sensing device to turn a decorative ornament on at night and then off during the day. To avoid inconsistent operation, it is often necessary to make sure the light sensing element does not react to the light emitted from the internal light source. A typical solution to this problem is to form an opening somewhere in the ornament and then place the light sensing device so that it reacts only to light entering through this opening and is generally shielded from the internal light source. While effective, the structures needed to place the light sensing device in the proper position and prevent water from entering the opening complicate the design and increase the cost of the ornament. Another solution to this problem is to turn the internal light off briefly while the light sensing device is measuring the ambient light levels. Those familiar with the art will understand that the intensity of a light source can be controlled using pulse width modulation (PWM). Typically the light source is turned on at full intensity for some period of time and then off for a second period of time. The ratio of these two times determines the perceived intensity of the light source. If the sum of these two times is consistent and less than about 30 mS, the light source will be perceived as a steady glow. If the sum of the two times is not consistent or longer than about 30 mS, the light source will appear to flicker in an undesirable manner. By activating the light sensing device only when the light source is turned off, it becomes possible to place the light sensing device in close proximity to the light source and still measure only the ambient light conditions. While this allows the light sensing device and light source to be placed in close proximity, it requires that the light sensing device operate quickly during the brief time the light source is off. This generally requires the light sensing device to operate at relatively high currents in order to charge the stray capacitance typically found in such sensors. These relatively high currents result in shortened battery life. Instead of operating the light sensing device during the periods of time when the PWM signal is off, it would be desirable to find another time when the light source could be periodically turned off without introducing a visible flicker.